Air-cooling cylinder head of gasoline engine and gasoline engine having the same

ABSTRACT

The invention discloses an air-cooling cylinder head of a gasoline engine and a gasoline engine. The air-cooling cylinder head of a gasoline engine comprises a cylinder head main body ( 1 ), and an intake passage ( 3 ), an exhaust passage ( 2 ) and a spark plug mounting hole ( 6 ) arranged in the cylinder head main body ( 1 ), a plurality of cooling fins ( 4 ) is arranged on the outer surface of the cylinder head main body ( 1 ), a combustion chamber surface ( 5 ) is formed on the inner side of the cylinder head main body ( 1 ), a longitudinally through air-cooling passage I ( 8 ) is arranged on the same side of the cylinder head main body ( 1 ) as the intake passage ( 3 ) and the exhaust passage ( 2 ), a transversally through air-cooling passage II ( 7 ) is arranged between the intake passage ( 3 ) and the exhaust passage ( 2 ), and both the longitudinally through air-cooling passage I ( 8 ) and the transversally through air-cooling passage II ( 7 ) are kept away from function holes on the cylinder head main body ( 1 ). In the technical solution of the invention, cooling air flows through the outer surface of the combustion chamber wall from different directions to sufficiently decrease the temperature of the combustion chamber, so that the cylinder head has excellent cooling efficiency, and the power of the gasoline engine is increased.

TECHNICAL FIELD OF THE INVENTION

The invention relates to the field of power machinery, in particular toan air-cooling cylinder head of a gasoline engine and a gasoline enginehaving the same.

BACKGROUND OF THE INVENTION

General-purpose gasoline engines are reciprocating piston gasolineengines with broad applications, except applications in vehicle andaeroplane. Generally, those with a power within 20 kW are called assmall general-purpose gasoline engines; and they have high generalityand advantages of small volume, small mass, simple and convenient useand operation, and low price. As one of power sources, thegeneral-purpose gasoline engine is used for driving general-purposemachinery, including agriculture and forestry plant protectionmachinery, garden machinery, power generation sets and constructionmachinery and the like. As a kind of power machinery using gasoline asfuel, the gasoline engine consists of a cylinder, a crank and connectingrod mechanism, a distribution system, an fuel supply system, alubrication system and an ignition system and the like. The cylinderhead is provided with an intake passage and an exhaust passage and formsa combustion chamber together with the cylinder; therefore it is a veryimportant component of the gasoline engine. The mixture of gasoline andair combusts in the combustion chamber, a lot of heat is generated andused as driving energy. The heat has to be inevitably transferredthrough the heat conduction of the cylinder body and the cylinder headto the outer surface and then transferred to the outside through othercooling manners, and quick cooling is required to maintain the normalworking of the combustion chamber surface; otherwise, limitless rise ofthe temperature of the combustion chamber wall surface may be caused,finally the tail gas emission may be influenced and the use of thecylinder head may be influenced, even piston sticking and scuffing ofcylinder may be caused.

In the prior art, as a cooling measure for the cylinder head,arrangement of cooling fins on the outer surface is generally adopted,the heat inside the combustion chamber is conducted to the cooling finsthrough the cylinder head, and taken away through air convection toachieve the purpose of cooling. Cooling fins have excellent coolingefficiency and small weight, so they can meet the cooling requirements.However, when the gasoline engine operates for a long time, as the heatconduction performance and the convection area of the cooling fins arelimited, cooling is insufficient; the accumulation of heat may influencethe physical performance of the cylinder head, further influence theoperating performance of the gasoline engine, even cause accidents andmake the gasoline engine scrapped.

Therefore, it is necessary to improve the air-cooling cylinder head ofthe gasoline engine, to make it have excellent cooling efficiency,guarantee the physical performance of the cylinder head, and decreasethe temperature of the cylinder, so that the gasoline engine can operatestably for a long time, the hydrocarbon in the tail gas can be decreasedeffectively, and piston sticking and scuffing of cylinder due to therise of temperature can be avoided.

SUMMARY OF THE INVENTION

Therefore, the invention provides an air-cooling cylinder head of agasoline engine and a gasoline engine having the same, to make thecylinder head have excellent cooling efficiency, guarantee the physicalperformance of the cylinder head, and decrease the temperature of thecylinder, so that the gasoline engine can operate stably for a longtime, the hydrocarbon in the tail gas can be decreased effectively, andpiston sticking and scuffing of cylinder due to the rise of temperaturecan be avoided.

The air-cooling cylinder head of a gasoline engine comprises a cylinderhead main body, and an intake passage, an exhaust passage and a sparkplug mounting hole arranged in the cylinder head main body, a pluralityof cooling fins is arranged on the outer surface of the cylinder headmain body, a combustion chamber surface is formed on the inner side ofthe cylinder head main body, a longitudinally through air-coolingpassage I is arranged on the same side of the cylinder head main body asthe intake passage and the exhaust passage, a transversally throughair-cooling passage II is arranged between the intake passage and theexhaust passage, and both the longitudinally through air-cooling passageI and the transversally through air-cooling passage II are kept awayfrom function holes on the cylinder head main body.

Further, the axis of the intake passage and the axis of the exhaustpassage are in a coplane, the air-cooling passage I is parallel to thecoplane of the axis of the intake passage and the axis of the exhaustpassage, the air-cooling passage I and the spark plug mounting hole arerespectively located on two sides of the coplane of the axis of theintake passage and the axis of the exhaust passage, the air-coolingpassage II is vertical to the coplane of the axis of the intake passageand the axis of the exhaust passage. The primary structure of thecylinder head can be utilized to achieve the design of the air-coolingpassages, and the air-cooling passage I and the air-cooling passage IIare vertical to each other, so that the cooling air can flow from alldirections, the mounting of all components is not influenced, and themanufacturing cost is saved; simultaneously, the design of theair-cooling passages in the structure is beneficial to improve thebending moment resistant capability of the cylinder head, in conjunctionwith the enhancement of the cooling efficiency, the cylinder head islight in weight, and the overall economy of the machine is improved.

Further, the cooling fins extends into the air-cooling passage I to forma cooling bridge, and the air-cooling passage I is separated into astructure with a plurality of parallel and longitudinal passages by thecooling bridge. The cooling bridge structure is beneficial to guaranteethe strength of the cylinder head after the air-cooling passage I isopened, simultaneously, through the cooling bridge, the heat radiationand conduction area during cooling is increased, which is furtherbeneficial to the cooling.

Further, a through spark plug air-cooling passage is arranged on thesame side of the cylinder head main body as the spark plug mountinghole. The spark plug can be cooled well by means of air cooling, and theproblem that the service life of the spark plug is decreased due to hightemperature in the prior art is avoided.

Further, the cooling fins on the cylinder head main body extends to theouter wall of the exhaust passage. This structure can decrease theexhaust temperature, which benefits to the protection of the tail gastreatment components inside the exhaust system, further reduce emissionand benefit to the environmental protection.

Further, the combustion chamber surface is of a complexly sphericalstructure comprising a sphere I, a smooth curve and a sphere II in turnfrom the bottom to the top, and the radius of the sphere II is largerthan that of the sphere I; and the sphere I and the sphere II are insmooth transition through the smooth curve. As the spherical combustionchamber surface has minimum surface to volume ratio, the workingefficiency of the gasoline engine is improved, however, as globalstructure is not beneficial to the sufficient mixing of combustiongases, the mixing efficiency is decreased, and combustion and emissionare influenced; the use of complex spherical structure not only furtherdecreases the surface to volume ratio, but also more benefits to thecombustion and reduction of emission as curve transition is beneficialto the mixing of combustion gases, so that the power of the gasolineengine is increased. Simultaneously, the included angles between theintake/exhaust valves and the intake/exhaust passages are smaller thanthose in combustion chamber surfaces of other structures, the resistancefor intake and exhaust is reduced effectively, so that intake andexhaust are smoother, the power of the gasoline engine is increasedeffectively, fuel consumption and emission are further reduced. It isadapted to the complex spherical combustion chamber, the included anglesbetween the intake/exhaust valves and the intake/exhaust passages aresmaller than those in the combustion chamber surface of the existingstructure, so that intake is organized conveniently, the intakeefficiency is improved, intake tumbling and intake swirl inside thecylinder are organized conveniently, current perturbation inside thecylinder is increased, and combustion is boosted. And the resistance forintake and exhaust is reduced, so that intake and exhaust are smoother,the power of the gasoline engine is increased effectively, the fuelconsumption is reduced, the tail gas emission is reduced, and theenvironment is protected.

Further, an intake valve is arranged on the cylinder head main bodycorrespondingly to the intake passage, an exhaust valve is arrangedcorrespondingly to the exhaust passage, the intake valve is oblique tothe intake passage side from the bottom to the top, and the exhaustvalve is oblique to the exhaust passage side from the bottom to the top.As the valves are obliquely arranged, the nose bridge region between theintake passage and the exhaust passage is wider, cooling is benefitedand the resistance to deformation is improved, with the completelythrough air-cooling passage II, the cooling efficiency of the nosebridge region is greatly improved, the deformation of the cylinder headunder high temperature is reduced, and the reliability is improved.

Further, the intake valve and the exhaust valve are respectivelyprovided with rocker arms, rocker arm bases are respectively arranged onthe cylinder head main body correspondingly to the corresponding rockerarms, the rocker arms are fixedly provided with corresponding rocker armshafts, the rocker arm shafts are arranged on the corresponding rockerarm bases in single freedom in a manner of capable of rotating aroundrespective axes, the rocker arm shafts are internally and obliquelyarranged towards the top in the radial direction with respect to themounting surface of the cylinder head main body, and the oblique angleof the corresponding rocker arm shafts with respect to the mountingsurface of the cylinder head main body is respectively andcorrespondingly identical to the oblique angles of the intake valve andthe exhaust valve with respect to the axis of the cylinder head mainbody; and the rocker arms form a lever structure using the correspondingrocker arm shafts as the fulcrums. The obliquely arranged rocker armshafts can be adapted to the structure of the obliquely arranged gasvalves and also to the geometric shape of the complex sphericalcombustion chamber, to guarantee the harmony and tightness of thedriving action of the valves by the rocker arms. The fixed rocker armshave small bouncing and rocking amount in all directions during theoperating process, the failure rate of the rocker arms can be decreasedeffectively, and the maintenance cost is reduced. The rocker arms aredisposed rationally to be adapted to the position of intake and exhaust,to guarantee the valve timing and the gas distribution phase, so thatthe performance is improved and the emission is reduced.

Further, the rocker arm bases are of structures with openings, the twoends of the rocker arm shafts are correspondingly inserted into the twosides of the openings of the corresponding rocker arm bases and therocker arm shafts fit with the corresponding rocker arm bases in amanner of capable of rotating around respective axes, and the rockerarms are located inside the openings of the corresponding rocker armbases and fixedly arranged on the corresponding rocker arm shafts; theoutward side of the opening structure of the rocker arm bases is a splitbearing base structure comprising a gland and a base body, and the glandand the base body are detachably and fixedly connected with each other.The use of the split bearing base structure is beneficial to themounting of the rocker arm shafts, the decrease of the friction area,and to the increase of the motion flexibility of the rocker arms. Thestructure is simple and compact, and the space is saved.

Further, the axis of the intake valve and the axis of the exhaust valveare respectively vertical to the tangent plane of the intersectionspoint of the combustion chamber surface with the axis of the intakevalve and the axis of the exhaust valve. This structure is adapted tothe intake and exhaust directions of the combustion chamber, so that theresistance is reduced, and the dynamic property of the gasoline engineis increased.

Further, the part of the combustion chamber surface located between theintake valve and the exhaust valve forms a nose bridge region, and thewidth of the nose bridge region is above 8mm on the combustion chambersurface. The distance between the intake valve and the exhaust valve isincreased, the thickness of the nose bridge region is properlyincreased, the capability of resisting against heat deformation isincreased, and the tightness of the valves is improved effectively sothat gas leakage of the valves can be avoided effectively.Simultaneously, instant interference between intake and exhaust isavoided, sufficient combustion is guaranteed, and the power of thegasoline engine is increased.

Further, the outer circle of a seat retainer of the intake valve and theouter circle of a seat retainer of the exhaust valve are tangent to theedge of the bottom of the combustion chamber surface; and the internalend of the seat retainer of the intake valve and the internal end of theseat retainer of the exhaust valve are matched with the shape of thecombustion chamber surface. As the internal end of the seat retainer ofthe intake valve and the internal end of the seat retainer of theexhaust valve are matched with the shape of the combustion chambersurface, interference to intake and exhaust can be decreased, theresistance is reduced, the dead angle and the sharp shape change areeliminated, the sufficient combustion of the mixed gases is guaranteed,and the efficiency of the gasoline engine is improved.

The invention also discloses a gasoline engine having the foregoingdescribed air-cooling cylinder head of a gasoline engine, wherein theair-cooling cylinder head of a gasoline engine is mounted in thegasoline engine.

The invention has the following beneficial effects: in the air-coolingcylinder head of a gasoline engine and the gasoline engine, hollowair-cooling passages are respectively arranged in the intake and exhaustdirections of the air-cooling cylinder head of a gasoline engine andalso in the directions vertical to the intake and exhaust directions, sothat cooling air can flow through the outer surface of the combustionchamber wall from different directions, simultaneously, heat istransferred outside by the walls of the passages by means of heatconduction, the conduction and convection area is increased tosufficiently decrease the temperature of the combustion chamber, so thatthe cylinder head has excellent cooling efficiency, the temperature ofthe cylinder is decreased, the hydrocarbon in the tail gas is reducedeffectively, and the power of the gasoline engine is increased. Take agasoline engine with a maximum power of 7.5 kW (revolving speed: 3060rpm) for example, the power can be increased to 8.1 kW, the emission canbe reduced to 6.0 g/kW.h from 8.0 g/kW.h, the standard of 8 g/kW.h inEPA3 stage is satisfied and exceeded, therefore it can be seen that theincrease of the power and the reduction of the emission of the gasolineengine are relatively obvious. No piston sticking and scuffing ofcylinder occurs in the gasoline engine in the invention, at the sametime that the performance of the gasoline engine is guaranteed, thegasoline engine also can operate stably for a long time. As air-cooingpassages are provided, the capability of the cylinder head itself toresist against the bending moment can be improved, in conjunction withgood cooling efficiency, physical performances of the cylinder head suchas resistance to deformation are guaranteed effectively, and the weightof the cylinder head can be properly reduced to achieve small weight ofthe gasoline engine.

The cylinder head is used in a gasoline engine. When the cylinder headis used in general-purpose power equipment driven by gasoline engines,the flowing of air inside the air-cooling passages can be accelerated,to be more conducive to cooling; and when it is used in commongeneral-purpose machinery, it is exposed in air, and cooling is conducedthrough externally forcible air convection.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further described below with reference to drawingsand embodiments.

FIG. 1 shows a structure view of the invention;

FIG. 2 shows a view of FIG. 1 along the direction A;

FIG. 3 shows the view of FIG. 2 along the direction B-B;

FIG. 4 shows a front view of the spark plug air-cooling passage;

FIG. 5 shows a mounting structure view of rocker arms;

FIG. 6 shows a sectional view of the coordination between rocker armshafts and rocker arm bases.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a structure view of the invention, FIG. 2 shows a view ofFIG. 1 along the direction A, FIG. 3 shows the view of FIG. 2 along thedirection B-B, FIG. 4 shows a front view of the spark plug air-coolingpassage, FIG. 5 shows a mounting structure view of rocker arms, and FIG.6 shows a sectional view of the coordination between rocker arm shaftsand rocker arm bases. As shown in the drawings: the air-cooling cylinderhead of a gasoline engine in the embodiment comprises a cylinder headmain body 1, and an intake passage 3, an exhaust passage 2 and a sparkplug mounting hole 6 arranged in the cylinder head main body 1, aplurality of cooling fins 4 is arranged on the outer surface of thecylinder head main body 1, a combustion chamber surface 5 is formed onthe inner side of the cylinder head main body 1, a longitudinallythrough air-cooling passage I 8 is arranged on the same side of thecylinder head main body 1 as the intake passage 3 and the exhaustpassage 2, a transversally through air-cooling passage II 7 is arrangedbetween the intake passage 3 and the exhaust passage 2, and both thelongitudinally through air-cooling passage I 8 and the transversallythrough air-cooling passage II 7 are kept away from function holes onthe cylinder head main body 1, the function holes are holes which areused for mounting components and which include a spark plug hole, anintake valve hole, an exhaust valve hole and bolt holes and the like;the longitudinal direction means a direction substantially identical tothe directions of intake and exhaust of the cylinder head main body; andthe transversal direction means a direction substantially vertical to acylinder head main body. The direction shown by the arrow in FIG. 3 isthe flowing direction of air.

In the embodiment, the axis of the intake passage 3 and the axis of theexhaust passage 2 are arranged in coplanar, that is, the axis of theintake passage 3 and the axis of the exhaust passage 2 are in a sameplane, in the invention, this plane is called coplane. the air-coolingpassage I 8 is parallel to the coplane of the axis of the intake passage3 and the axis of the exhaust passage 2, the air-cooling passage I 8 andthe spark plug mounting hole 6 are respectively located on two sides ofthe coplane of the axis of the intake passage 3 and the axis of theexhaust passage 2, the air-cooling passage II 7 is vertical to thecoplane of the axis of the intake passage 3 and the axis of the exhaustpassage 2. The primary structure of the cylinder head can be utilized toachieve the design of the air-cooling passages and the air-coolingpassage I 8 and the air-cooling passage II 7 are vertical to each other,so that the cooling air can flow from all directions, the mounting ofall components is not influenced, and the manufacturing cost is saved.Simultaneously, the design of the air-cooling passages in the structureis beneficial to improve the bending moment resistant capability of thecylinder head, in conjunction with the enhancement of the coolingefficiency, the cylinder head is light in weight, and the overalleconomy of the machine is improved.

In the embodiment, as shown in FIG. 2 and FIG. 3, the cooling fins 4extends into the air-cooling passage I 8 to form a cooling bridge 81,and the air-cooling passage I 8 is separated into a structure with aplurality of parallel and longitudinal passages by the cooling bridge81. The structure of cooling bridge 81 is beneficial to guarantee thestrength of the cylinder head after the air-cooling passage I 8 isopened. Simultaneously, through the cooling bridge 81, the heatradiation and conduction area during cooling is increased, which isfurther beneficial to the cooling.

In the embodiment, a through spark plug air-cooling passage 9 isarranged on the same side of the cylinder head main body 1 as the sparkplug mounting hole 6. The direction shown by the arrow in FIG. 5 is theflowing direction of the spark plug cooling air. The spark plug can becooled well by means of air cooling, and the problem that the servicelife of the spark plug is decreased due to high temperature in the priorart is avoided.

In the embodiment, the cooling fins 4 on the cylinder head main bodyextends to the outer wall of the exhaust passage 2. This structure candecrease the exhaust temperature, which benefits to the protection ofthe tail gas treatment components inside the exhaust system, furtherreduce emission and benefit to the environmental protection.

The combustion chamber surface 5 is of a complexly spherical structurecomprising a sphere I a, a smooth curve b and a sphere II c in turn fromthe bottom to the top, and the radius of the sphere II c is larger thanthat of the sphere I a; and the sphere I a and the sphere II c are insmooth transition through the smooth curve b. The smooth curve b may bea hyperboloid or paraboloid. As the spherical combustion chamber surfacehas minimum surface to volume ratio, the working efficiency of thegasoline engine is improved. However, as global structure is notbeneficial to the sufficient mixing of combustion gases, the mixingefficiency is decreased, and combustion and emission are influenced. Theuse of complex spherical structure not only further decreases thesurface to volume ratio, but also more benefits to the combustion andreduction of emission as curve transition is beneficial to the mixing ofcombustion gases, so that the power of the gasoline engine is increased.Simultaneously, the included angles between the intake/exhaust valvesand the intake/exhaust passages are smaller than those in combustionchamber surfaces of other structures, the resistance for intake andexhaust is reduced effectively, so that intake and exhaust are smoother,the power of the gasoline engine is increased effectively, fuelconsumption and emission are further reduced.

In the embodiment, an intake valve 31 is arranged on the cylinder headmain body 1 correspondingly to the intake passage 3, an exhaust valve 21is arranged correspondingly to the exhaust passage 2, the intake valve31 is oblique to the intake passage 3 side from the bottom to the top,and the exhaust valve 21 is oblique to the exhaust passage 2 side fromthe bottom to the top. It is adapted to the complex spherical combustionchamber, the included angles between the intake/exhaust valves and theintake/exhaust passages are smaller than those in the combustion chambersurface of the existing structure, so that intake is organizedconveniently, the intake efficiency is improved, intake tumbling andintake swirl inside the cylinder are organized conveniently, currentperturbation inside the cylinder is increased, and combustion isboosted. And the resistance for intake and exhaust is reduced, so thatintake and exhaust are smoother, the power of the gasoline engine isincreased effectively, the fuel consumption is reduced, the tail gasemission is reduced, and the environment is protected.

Simultaneously, as the valves are obliquely arranged, the nose bridgeregion between the intake passage and the exhaust passage is wider,cooling is benefited and the resistance to deformation is improved, withthe completely through air-cooling passage II 7, the cooling efficiencyof the nose bridge region is greatly improved, the deformation of thecylinder head under high temperature is reduced, and the reliability isimproved.

The intake valve 31 and the exhaust valve 21 are respectively providedwith rocker arms, as shown in FIG. 5: the rock arm of the intake valve31 is represented by 11 and the rocker arm of the exhaust valve 21 isrepresented by 13; rocker arm bases (rocker arm base 15 and rocker armbase 12 in FIG. 5) are arranged on the cylinder head main body 1correspondingly to the rocker arms (rocker arm 11 and rocker arm 13),the rocker arms (rocker arm 11 and rocker arm 13) are respectively andfixedly provided with rocker arm shafts (rocker arm shaft 10 and rockerarm shaft 14), the rocker arm shafts (rocker arm shaft 10 and rocker armshaft 14) are correspondingly arranged on the rocker arm bases (rockerarm base 15 and rocker arm base 12) in single freedom in a manner ofcapable of rotating around respective axes, the rocker arm shafts(rocker arm shaft 10 and rocker arm shaft 14) are internally andobliquely arranged towards the top in the radial direction with respectto the mounting surface of the cylinder head main body 1, and the radialdirection means the radial direction of the cylinder head; the obliqueangle of the corresponding rocker arm shafts (rocker arm shaft 10 androcker arm shaft 14) with respect to the mounting surface of thecylinder head main body 1 is respectively and correspondingly identicalto the oblique angles of the intake valve 31 and the exhaust valve 21with respect to the axis of the cylinder head main body 1; and therocker arms (rocker arm 11 and rocker arm 13) form a lever structureusing the corresponding rocker arm shafts (rocker arm shaft 10 androcker arm shaft 14) as the fulcrums, and the rocker arms form obliquelyfixed rocker arms together with the rocker arm shafts.

The obliquely arranged rocker arm shafts can be adapted to the structureof the obliquely arranged gas valves and also to the geometric shape ofthe complex spherical combustion chamber, to guarantee the harmony andtightness of the driving action of the valves by the rocker arms, thefixed rocker arms have small bouncing and rocking amount in alldirections during the operating process, the failure rate of the rockerarms can be decreased effectively, and the maintenance cost is reduced.

The rocker arms are disposed rationally to be adapted to the position ofintake and exhaust, to guarantee the valve timing and the gasdistribution phase, so that the performance is improved and the emissionis reduced.

In the embodiment, the rocker arm bases (rocker arm base 15 and rockerarm base 12) are of structures with openings, the two ends of the rockerarm shafts (rocker arm shaft 10 and rocker arm shaft 14) arecorrespondingly inserted into the two sides of the openings of thecorresponding rocker arm bases (rocker arm base 15 and rocker arm base12) and the rocker arm shafts fit with the corresponding rocker armbases in a manner of capable of rotating around respective axes. Singlefreedom means that the axial degree of freedom of the rocker arm shaftsis limited, a structure in which shoulders are arranged on the rockerarm shafts to lean against two sides of the openings of thecorresponding rocker arm bases may be adopted, or any manner which canlimit axial movement and allow circumferential sliding in the prior artmay be adopted. The rocker arms (rocker arm 11 and rocker arm 13) arelocated inside the openings of the corresponding rocker arm bases(rocker arm base 15 and rocker arm base 12) and fixedly arranged on thecorresponding rocker arm shafts (rocker arm shaft 10 and rocker armshaft 14); the outward side of the opening structure of the rocker armbase 15 (and rocker arm base 12) is a split bearing base structure. Asshown in FIG. 6, the outward side of the opening structure of the rockerarm base 15 comprises a gland 151 a and a base body 151, and the gland151 a and the base body 151 are detachably and fixedly connected witheach other, they are connected through bolts in the embodiment. Bearingsbush 101 also can be arranged to reduce friction, the inward side of theopening structure of the rocker arm base 15 (and rocker arm base 12) isalso provided with bearing bushes correspondingly. The outward side ofthe opening structure of the rocker arm base 12 is the same as theoutward side of the opening structure of the rocker arm base 15. The useof the split bearing base structure is beneficial to the mounting of therocker arm shafts, the decrease of the friction area and to the increaseof the motion flexibility of the rocker arms; and, the structure issimple and compact, and the space is saved.

In the embodiment, the axis of the intake valve 31 and the axis of theexhaust valve 21 are respectively vertical to the tangent plane of theintersections point of the combustion chamber surface 5 with the axis ofthe intake valve 31 and the axis of the exhaust valve 21, that is, theaxis of the intake valve 31 and the axis of the exhaust valve 21 arerespectively intersected with the combustion chamber surface 5, and theintersection points are in the tangent plane of the combustion chambersurface 5. That is, the axes of the intake valve 31 and the exhaustvalve 21 are intersected in the center of the combustion chamber, whichis adapted to the intake and exhaust directions of the combustionchamber, so that the resistance is reduced, and the dynamic property ofthe gasoline engine is increased.

In the embodiment, the part of the combustion chamber surface 5 locatedbetween the intake valve 31 and the exhaust valve 21 forms a nose bridgeregion, as shown in FIG. 1, the width L of the nose bridge region isabove 8mm on the combustion chamber surface 5. The outer circle of aseat retainer 31 a of the intake valve 31 and the outer circle of a seatretainer 21 a of the exhaust valve 21 are tangent to the edge of thebottom of the combustion chamber surface 5. The distance between theintake valve 31 and the exhaust valve 21 is increased, the thickness ofthe nose bridge region is properly increased, the capability ofresisting against heat deformation is increased, and the tightness ofthe valves is improved effectively so that gas leakage of the valves canbe avoided effectively. Simultaneously, instant interference betweenintake and exhaust is avoided, sufficient combustion is guaranteed, andthe power of the gasoline engine is increased. The internal end of theseat retainer 31 a of the intake valve 31 and the internal end of theseat retainer 21 a of the exhaust valve 21 are matched with the shape ofthe combustion chamber surface 5. The end surface shapes of the internalend of the seat retainer 31 a of the intake valve 31 and the internalend of the seat retainer 21 a of the exhaust valve 21 are matched withthe shape of the combustion chamber surface, stairs are removed,interference to intake and exhaust can be decreased, the resistance isreduced, the dead angle and the sharp shape change are eliminated, thesufficient combustion of the mixed gases is guaranteed, and theefficiency of the gasoline engine is improved.

The invention also discloses a gasoline engine having the foregoingdescribed air-cooling cylinder head of a gasoline engine, wherein theair-cooling cylinder head of a gasoline engine is mounted in thegasoline engine.

The gasoline engine in the invention is mainly used in general-purposemachinery mainly including driving water pumps, fans and powergenerators and the like, with excellent cooling efficiency.

Finally, it should be noted that above embodiment is just used forexplaining but not limiting the technical solution of the invention;although the invention has been described in details with reference tothe preferred embodiment, it should be understood by common techniciansin the field that the technical solution of the invention may havemodifications or equivalent replacements within the principle and scopeof the technical solution of the invention, and those modifications orequivalent replacements should be included in the protection scope ofthe invention.

1. An air-cooling cylinder head of a gasoline engine, comprising acylinder head main body, and an intake passage, an exhaust passage and aspark plug mounting hole arranged in the cylinder head main body, aplurality of cooling fins is arranged on the outer surface of thecylinder head main body, and a combustion chamber surface is formed onthe inner side of the cylinder head main body, wherein a longitudinallythrough air-cooling passage I is arranged on the same side of thecylinder head main body as the intake passage and the exhaust passage, atransversally through air-cooling passage II is arranged between theintake passage and the exhaust passage, and both the longitudinallythrough air-cooling passage I and the transversally through air-coolingpassage II are kept away from function holes on the cylinder head mainbody.
 2. The air-cooling cylinder head of a gasoline engine according toclaim 1, wherein the axis of the intake passage and the axis of theexhaust passage are in a coplane, the air-cooling passage I is parallelto the coplane of the axis of the intake passage and the axis of theexhaust passage, the air-cooling passage I and the spark plug mountinghole are respectively located on two sides of the coplane of the axis ofthe intake passage and the axis of the exhaust passage, the air-coolingpassage II is vertical to the coplane of the axis of the intake passageand the axis of the exhaust passage.
 3. The air-cooling cylinder head ofa gasoline engine according to claim 2, wherein the cooling fins extendsinto the air-cooling passage I to form a cooling bridge, and theair-cooling passage I is separated into a structure with a plurality ofparallel and longitudinal passages by the cooling bridge.
 4. Theair-cooling cylinder head of a gasoline engine according to claim 3,wherein a through spark plug air-cooling passage is arranged on the sameside of the cylinder head main body as the spark plug mounting hole. 5.The air-cooling cylinder head of a gasoline engine according to claim 4,wherein the cooling fins on the cylinder head main body extends to theouter wall of the exhaust passage.
 6. The air-cooling cylinder head of agasoline engine according to claim 1, wherein the combustion chambersurface is of a complexly spherical structure comprising a sphere I (a),a smooth curve (b) and a sphere II (c) in turn from the bottom to thetop, and the radius of the sphere II (c) is larger than that of thesphere I (a); and the sphere I (a) and the sphere II (c) are in smoothtransition through the smooth curve (b).
 7. The air-cooling cylinderhead of a gasoline engine according to claim 6, wherein an intake valveis arranged on the cylinder head main body correspondingly to the intakepassage, an exhaust valve is arranged correspondingly to the exhaustpassage, the intake valve is oblique to the intake passage side from thebottom to the top, and the exhaust valve is oblique to the exhaustpassage side from the bottom to the top.
 8. The air-cooling cylinderhead of a gasoline engine according to claim 7, wherein the intake valveand the exhaust valve are respectively provided with rocker arms, rockerarm bases are respectively arranged on the cylinder head main bodycorrespondingly to the corresponding rocker arms, the rocker arms arefixedly provided with corresponding rocker arm shafts, the rocker armshafts are arranged on the corresponding rocker arm bases in singlefreedom in a manner of capable of rotating around respective axes, therocker arm shafts are internally and obliquely arranged towards the topin the radial direction with respect to the mounting surface of thecylinder head main body, and the oblique angle of the correspondingrocker arm shafts with respect to the mounting surface of the cylinderhead main body is respectively and correspondingly identical to theoblique angles of the intake valve and the exhaust valve with respect tothe axis of the cylinder head main body; and the rocker arms form alever structure using the corresponding rocker arm shafts as thefulcrums.
 9. The air-cooling cylinder head of a gasoline engineaccording to claim 8, wherein the rocker arm bases are of structureswith openings, the two ends of the rocker arm shafts are correspondinglyinserted into the two sides of the openings of the corresponding rockerarm bases, and the rocker arm shafts fit with the corresponding rockerarm bases in a manner of capable of rotating around respective axes, andthe rocker arms are located inside the openings of the correspondingrocker arm bases and fixedly arranged on the corresponding rocker armshafts; the outward side of the opening structure of the rocker armbases is a split bearing base structure comprising a gland and a basebody, and the gland and the base body are detachably and fixedlyconnected with each other.
 10. The air-cooling cylinder head of agasoline engine according to claim 9, wherein the axis of the intakevalve and the axis of the exhaust valve are respectively vertical to thetangent plane of the intersections point of the combustion chambersurface with the axis of the intake valve and the axis of the exhaustvalve.
 11. The air-cooling cylinder head of a gasoline engine accordingto claim 10, wherein the part of the combustion chamber surface locatedbetween the intake valve and the exhaust valve forms a nose bridgeregion, and the width of the nose bridge region is above 8mm on thecombustion chamber surface.
 12. The air-cooling cylinder head of agasoline engine according to claim 11, wherein the outer circle of aseat retainer of the intake valve and the outer circle of a seatretainer of the exhaust valve are tangent to the edge of the bottom ofthe combustion chamber surface; and the internal end of the seatretainer of the intake valve and the internal end of the seat retainerof the exhaust valve are matched with the shape of the combustionchamber surface.
 13. A gasoline engine having the air-cooling cylinderhead of a gasoline engine according to claim 1, wherein the air-coolingcylinder head of a gasoline engine is arranged in the gasoline engine.14. The air-cooling cylinder head of a gasoline engine according toclaim 5, wherein the combustion chamber surface is of a complexlyspherical structure comprising a sphere I (a), a smooth curve (b) and asphere II (c) in turn from the bottom to the top, and the radius of thesphere II (c) is larger than that of the sphere I (a); and the sphere I(a) and the sphere II (c) are in smooth transition through the smoothcurve (b).
 15. A gasoline engine having the air-cooling cylinder head ofa gasoline engine according to claim 2, wherein the air-cooling cylinderhead of a gasoline engine is arranged in the gasoline engine.
 16. Agasoline engine having the air-cooling cylinder head of a gasolineengine according to claim 3, wherein the air-cooling cylinder head of agasoline engine is arranged in the gasoline engine.
 17. A gasolineengine having the air-cooling cylinder head of a gasoline engineaccording to claim 4, wherein the air-cooling cylinder head of agasoline engine is arranged in the gasoline engine.
 18. A gasolineengine having the air-cooling cylinder head of a gasoline engineaccording to claim 5, wherein the air-cooling cylinder head of agasoline engine is arranged in the gasoline engine.
 19. A gasolineengine having the air-cooling cylinder head of a gasoline engineaccording to claim 6, wherein the air-cooling cylinder head of agasoline engine is arranged in the gasoline engine.
 20. A gasolineengine having the air-cooling cylinder head of a gasoline engineaccording to claim 8, wherein the air-cooling cylinder head of agasoline engine is arranged in the gasoline engine.